1. Field of the Invention
This invention relates to a process for producing a roller equipped with a rubber layer to be used as a constituting part of a conveying means of various articles or for a platen roller which is a printing means for typewriters, etc.
2. Related Background Art
A roller equipped with a rubber layer having a rubber layer provided around the circumferential wall of a core metal having primarily a columnar outer shape has been utilized as, for example, a constituting part of a conveying means of various articles or as a platen roller of the printing means for typewriters, etc.
Such a roller equipped with a rubber layer has been produced primarily according to a process using a cross-head extrusion molding machine.
A cross-head extrusion molding machine typically has a structure as shown in FIGS. 2A and 2B, and when rubber material 2 and core metal 3 are fed through separate feeding inlets, the rubber material 2 is extruded around the core metal 3 delivered in the cross-head 4, and further under the state coated around the circumferential wall of the core metal 3 delivered together with the core metal 3 from the outlet of the cross-head.
the core metal coated with the rubber material thus obtained is subsequently subjected to, for example, the steps as shown below to become a roller equipped with a rubber layer as the final product.
(a) The rubber material on the core metal is cut to a constant dimension.
(b) The rubber is vulcanized directly with vapor in a vulcanizing can.
(c) The end faces of the core metal are cut as protruded.
(d) The rubber layer surface coated on the core metal is finished by surface polishing.
According to the process for producing a roller equipped with a rubber layer according to the steps of the prior art as described above, the rubber material surface after cross-head extrusion molding is liable to become rough, and generation of unevenness is marked and yet it is similar even in the rubber layer obtained after vulcanization, and therefore polishing treatment of the rubber layer surface as the secondary working is essentially required.
Also, in the polishing treatment of the rubber layer surface, desired surface roughness for smoothness cannot be necessarily obtained on the rubber layer surface in some cases, and in many cases, the worked surface may become rougher although unevenness in outer diameter irregularity may be connected.
The present invention has been accomplished in view of such problems, and its object is to provide a process for producing a roller equipped with a rubber layer which can realize low cost by reducing the number of steps by omitting the polishing treatment of the rubber layer surface as the secondary working, and also can easily obtain desired smoothness or surface roughness on the rubber layer surface.